IMO, Bio Balls are better then scrubbies if cost is not an issue. If you are concerned about price, scrubbies are an excellent choice. You can get into the whole surface area of bio ball vs the surface area of scrubbies debate all day long but bio balls use all of the surface area provided because of the way water travel through the ball where water goes pretty much straight through a scrubbie wasting surface area. I am a fan of Poret foam for bio filtration. That is about all I have in my tank for bio filtration.